Preparation of high concentration polyaluminum chloride by chemical synthesis-membrane distillation method with self-made hollow fiber membrane

摘要

A method of direct contact membrane distillation (DCMD) with a self-made hollow polyvinylidene fluoride membrane was applied to prepare high concentration polyaluminum chloride (PACl) with high Al-b content based on chemical synthesis. The permeate flux and Al species distribution were investigated. The experimental results showed that the permeate flux decreased from 14 to 6 kg/(m(2).hr) at the end of the DCMD process, which can be mainly attributed to the formation of NaCl deposits on the membrane surface. The Al-b content decreased slightly, only from 86.3% to 84.4%, when the DCMD experiment finished, correspondingly the Al-c content increased slightly from 7.2% to 8.5%, and the Al-a content remained at 7% during the whole DCMD process. A PACl with Al-b content of 84% at total aluminum concentration 2.2 mol/L was successfully prepared by the chemical synthesis-DCMD method.